This invention relates to a process for preparing polymeric oximes. More particularly, it relates to certain hydrogen-protected monomeric oxime derivatives and to the production of polymeric oximes therefrom.
Polymeric oximes which may be characterized as polymers including an oximino group of the formula &gt;C.dbd.N--OH are known and are described, for example, in U.S. Pat. No. 3,268,480 (issued Aug. 23, 1966 to A. H. Wagernaar et al.) and in U.S. Pat. No. 4,202,694 (issued May 13, 1980 to L. D. Taylor). In general, polymeric oximes are prepared by first preparing a polymer of a polymerizable monomeric compound containing at least one carbonyl (&gt;C.dbd.O) group and, then, oximating the polymer with hydroxylamine reagent so as to convert carbonyl groups to oximino groups.
The preparation of certain polymeric oximes by the method of polymerizing a monomeric oxime has also been reported. In a series of publications by Masuda et al., in Polymer Journal, Vol. 11, No. 8, pp. 641-649 (1979); Vol. 11, No. 3, pp. 213-218 (1979); Vol. 10, No. 4, pp. 397-402 (1978); and in publications referenced therein, there is described the polymerization of acrolein oxime in organic solvent systems employing various means of initiating the polymerization reaction. The molecular weights of the polymers obtained were reported to be very low, generally about 1000 to 3000. The copolymerization of p-vinylacetophenone oxime with styrene and methylmethacrylate and p-isopropenylacetophenone oxime with styrene using ethyl alcohol or alcohol-benzene as a solvent is reported by B. A. Zaitsev and G. A. Shtraikhman in Vysokomol. soyed., A10: No. 2, 434-445 (1968), English translation at page 511. Molecular weights of the resulting polymers are not reported. In the aforementioned U.S. Pat. No. 4,202,694, reference is made to certain unsuccessful attempts to prepare high molecular weight polymers by polymerization of a monomeric oxime.
Owing to an apparent tendency of the oximino group of an ethylenically unsaturated monomeric oxime to exert an inhibiting effect upon the polymerization of the monomeric oxime and the resulting production, in general, of low molecular weight polymers, resort is made to the aforementioned method whereby a polymer is first prepared from a polymerizable monomer containing a carbonyl group and the resulting polymer is, then, subjected to an oximation procedure. This method may, however, impose limitations on the production of certain polymeric oximes. For example, it is oftentimes desirable to introduce water-solubilizing groups or other specific functionality into a polymeric oxime. Thus, copolymers of the carbonyl-containing monomer and a copolymerizable monomer will be prepared and then subjected to oximation conditions which may exert a hydrolytic or other adverse effect upon the recurring units introduced by the copolymerizable monomer. Moreover, the completeness of conversion of carbonyl-to-oximino groups can vary with the nature of the oximation conditions and the polymer such that it may be desirable to provide oximino groups in a polymer in controlled manner and as a function of a polymerizable oxime monomer.